1. Field of the Invention
This invention relates generally to electronic devices, and more particularly, to electronic devices containing accelerometers and capacitive touch sensors, wherein input from the accelerometers is used to select an improved sensitivity level at which the capacitive touch sensors operate, as well as a method for operating a device with such architecture.
2. Description of the Related Art
The following descriptions and examples are not admitted to be prior art by virtue of their inclusion within this section.
Capacitive touch sensors are increasing in popularity due to their performance advantages over resistive touch sensors. Unlike capacitive touch sensors, resistive touch sensors can deteriorate and become less dependable over time. This is because they require physical displacement and pressure on a plastic screen, which makes them susceptible to wear-out, corrosion and scratching. Capacitive touch sensors are less susceptible to these drawbacks, and have become a common alternative to resistive touch sensors. In particular, capacitive touch screens have a great deal of utility in particular applications, such as tablet computers and other portable electronic devices, because of their increased robustness, their ability to sense two or more simultaneous touches on different parts of a touch screen, and their ability to work better alongside a digitizer.
In its basic form, a capacitive touch sensor, such as a touch screen for an electronic device may comprise a layer of conductive coating (such as a thin-film conductive coating) on a glass substrate. The conductive coating is most commonly formed from indium tin oxide (ITO), but other transparent conductive oxides (TCOs), such as antimony tin oxide and zinc oxide may be used instead of ITO. The glass substrate may have an exterior coating that makes it more difficult to scratch and easier to clean than conventional touch screens, and may also function to seal the sensor electronics within the device.
The functionality of a capacitive touch screen is derived from circuits located along the edges of the screen that generate a uniform low-voltage electrical field over the conductive coating. When a person touches the screen with their finger, their finger will disrupt the electrical field. The disruption of the change in current flowing from each side of the touch screen can be measured, allowing the device to calculate the X and Y coordinates of the point on the screen the person touched.
Despite the rise in popularity of capacitive touch screens, these devices still suffer from some drawbacks. In particular, the touch screen devices tend to function well at a normal sensitivity levels when they are connected to either a power cord or the body of a user. The sensitivity level of a capacitive touch sensor refers generally to the device's ability to sense a touch. A device operating at low sensitivity is less likely to sense a touch than a device with high sensitivity. When a touch screen device is not in the hands of a user or connected via a power cord, it may need to operate at a heightened sensitivity level in order to accurately sense a user's touch. However, this heightened sensitivity level is accompanied by unwanted side effects. Accordingly, there is a need for managing the sensitivity level of a touch screen device to minimize the extent to which a user experiences the negative effects of operating at the heightened sensitivity level.